<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            margin: 0;
            height: 100vh;
            position: relative;
            background: pink;
            overflow: hidden;
        }

        #mask {
            width: 100%;
            height: 100%;
            position: absolute;
            top: 0;
            left: 0;
            background: #000;
            mix-blend-mode: multiply;
        }

        #mask::after,
        #mask::before {
            content: '';
            position: absolute;
            width: 80px;
            height: 300px;
            background: #fff;
            left: 50%;
            top: 50%;
            transform: translate(-50%, -50%) skew(45deg);
        }

        #mask::before {
            transform: translate(-50%, -50%) skew(-45deg);
        }
    </style>
</head>

<body>
    <div id="container">
        <video src=""></video>
        <div id="mask"></div>
    </div>
</body>
<script>
    var scale = 25;
    var mask = document.querySelector('#mask');
    var int = setInterval(() => {
        scale -= 0.1;
        mask.style.transform = 'scale(' + scale + ')';
        if (scale < 1) {
            scale = 1;
            clearInterval(int);
        }
    }, 1)
</script>

</html>